pytorch - ✅(Solved) Fix torch.compile degrades the performance compared with eager execution [1 pull requests, 1 comments, 2 participants]

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pytorch/pytorch#179697Fetched 2026-04-09 07:50:28
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Error Message

import argparse import time import torch import torch.nn.functional as F import torch.nn as nn

def calculate_token_entropy( logits: torch.Tensor, temperature: float = 1.0 ) -> torch.Tensor: if temperature == 0.0: if logits.dim() == 1: return torch.tensor(0.0, device=logits.device) return torch.zeros(logits.shape[0], device=logits.device)

scaled_logits = logits / temperature
probs = torch.softmax(scaled_logits, dim=-1)
log_probs = torch.log_softmax(scaled_logits, dim=-1)  
entropy = -torch.sum(probs * log_probs, dim=-1)
return entropy

def benchmark(fn, logits, temp, warmup=20, iters=100): for _ in range(warmup): fn(logits, temp)

if torch.cuda.is_available():
    torch.cuda.synchronize()

start_time = time.perf_counter()
for _ in range(iters):
    fn(logits, temp)

if torch.cuda.is_available():
    torch.cuda.synchronize()
end_time = time.perf_counter()

return ((end_time - start_time) / iters) * 1000

def main() -> None: parser = argparse.ArgumentParser() parser.add_argument("--batch-size", type=int, default=1) parser.add_argument("--vocab-size", type=int, default=32768) parser.add_argument("--device", type=str, default="cuda" if torch.cuda.is_available() else "cpu") parser.add_argument("--dtype", type=str, default="float16") args = parser.parse_args()

device = torch.device(args.device)
dtype = torch.float16 if args.dtype == "float16" else torch.float32

logits = torch.randn(args.batch_size, args.vocab_size, device=device, dtype=dtype)
temp = 1.0

print(f"Device: {device} | Dtype: {dtype} | Batch: {args.batch_size}")

configs = [
    ("Eager_Orig", calculate_token_entropy, None),
    ("Comp_Orig_Default", torch.compile(calculate_token_entropy), None),
    ("Comp_Orig_ReduceO", torch.compile(calculate_token_entropy, mode="reduce-overhead"), None),
    ("Comp_Orig_MaxTune", torch.compile(calculate_token_entropy, mode="max-autotune"), None),
]

results = []
for name, fn, _ in configs:
    try:
        fn(logits, temp)
        ms = benchmark(fn, logits, temp)
        results.append((name, ms))
    except Exception as e:
        results.append((name, None, str(e)[:50]))

baseline_orig = next(ms for name, ms in results if name == "Eager_Orig")

# ------ 0. Print speedup result ------
for row in results:
    if len(row) == 3:
        name, _, err = row
        print(f"{name:20s}: Failed -> {err}")
    else:
        name, ms = row
        baseline = baseline_orig
        speedup = baseline / ms
        print(f"{name:20s}: {ms:8.4f} ms  speedup={speedup:.3f}x")

if name == "main": main()

Fix Action

Fix / Workaround

CPU: Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Address sizes: 46 bits physical, 48 bits virtual Byte Order: Little Endian CPU(s): 96 On-line CPU(s) list: 0-95 Vendor ID: GenuineIntel Model name: Intel(R) Xeon(R) Gold 6248R CPU @ 3.00GHz CPU family: 6 Model: 85 Thread(s) per core: 2 Core(s) per socket: 24 Socket(s): 2 Stepping: 7 BogoMIPS: 6000.00 Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts vnmi pku ospke avx512_vnni md_clear flush_l1d arch_capabilities Virtualization: VT-x L1d cache: 1.5 MiB (48 instances) L1i cache: 1.5 MiB (48 instances) L2 cache: 48 MiB (48 instances) L3 cache: 71.5 MiB (2 instances) NUMA node(s): 2 NUMA node0 CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94 NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95 Vulnerability Gather data sampling: Mitigation; Microcode Vulnerability Itlb multihit: KVM: Mitigation: VMX disabled Vulnerability L1tf: Not affected Vulnerability Mds: Not affected Vulnerability Meltdown: Not affected Vulnerability Mmio stale data: Mitigation; Clear CPU buffers; SMT vulnerable Vulnerability Reg file data sampling: Not affected Vulnerability Retbleed: Mitigation; Enhanced IBRS Vulnerability Spec rstack overflow: Not affected Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization Vulnerability Spectre v2: Mitigation; Enhanced / Automatic IBRS; IBPB conditional; RSB filling; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop Vulnerability Srbds: Not affected Vulnerability Tsx async abort: Mitigation; TSX disabled

PR fix notes

PR #179729: [inductor] Raise split reduction threshold from 8K to 524K on Blackwell+

Description (problem / solution / changelog)

The split reduction heuristic was too aggressive for small-batch, moderate-reduction workloads (e.g. entropy/softmax over vocab=32K). With the old threshold of 8192, a batch=1 entropy computation over 32K vocab was split into 8 kernel launches (4 CTAs + tree-reduce for each of the 3 reduction steps), making torch.compile 2x slower than eager.

Raising the threshold to 524K on Blackwell (SM >= 10.0) avoids unnecessary splitting for practical softmax/entropy/layernorm vocab sizes while preserving splits for truly large reductions (>1M) where single-CTA throughput becomes a bottleneck. Older architectures retain the original 8192 threshold.

Benchmark on GB200 (global sum, batch=1): n=32K: split 0.047ms → nosplit 0.036ms (-25%) n=524K: split 0.040ms → nosplit 0.032ms (-19%) n=1M: split 0.042ms → nosplit 0.050ms (+18%, still splits with new threshold) n=8M: split 0.042ms → nosplit 0.595ms (regression, still splits with new threshold)

Fixes https://github.com/pytorch/pytorch/issues/179697

cc @voznesenskym @penguinwu @EikanWang @jgong5 @Guobing-Chen @XiaobingSuper @zhuhaozhe @blzheng @wenzhe-nrv @jiayisunx @ipiszy @kadeng @muchulee8 @amjames @chauhang @aakhundov @coconutruben @jataylo

Changed files

  • torch/_inductor/choices.py (modified, +6/-1)

Code Example

import argparse
import time
import torch
import torch.nn.functional as F
import torch.nn as nn

def calculate_token_entropy(
    logits: torch.Tensor, temperature: float = 1.0
) -> torch.Tensor:
    if temperature == 0.0:
        if logits.dim() == 1:
            return torch.tensor(0.0, device=logits.device)
        return torch.zeros(logits.shape[0], device=logits.device)

    scaled_logits = logits / temperature
    probs = torch.softmax(scaled_logits, dim=-1)
    log_probs = torch.log_softmax(scaled_logits, dim=-1)  
    entropy = -torch.sum(probs * log_probs, dim=-1)
    return entropy

def benchmark(fn, logits, temp, warmup=20, iters=100):
    for _ in range(warmup):
        fn(logits, temp)
    
    if torch.cuda.is_available():
        torch.cuda.synchronize()
    
    start_time = time.perf_counter()
    for _ in range(iters):
        fn(logits, temp)
    
    if torch.cuda.is_available():
        torch.cuda.synchronize()
    end_time = time.perf_counter()
    
    return ((end_time - start_time) / iters) * 1000

def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("--batch-size", type=int, default=1)
    parser.add_argument("--vocab-size", type=int, default=32768)
    parser.add_argument("--device", type=str, default="cuda" if torch.cuda.is_available() else "cpu")
    parser.add_argument("--dtype", type=str, default="float16")
    args = parser.parse_args()

    device = torch.device(args.device)
    dtype = torch.float16 if args.dtype == "float16" else torch.float32
    
    logits = torch.randn(args.batch_size, args.vocab_size, device=device, dtype=dtype)
    temp = 1.0

    print(f"Device: {device} | Dtype: {dtype} | Batch: {args.batch_size}")

    configs = [
        ("Eager_Orig", calculate_token_entropy, None),
        ("Comp_Orig_Default", torch.compile(calculate_token_entropy), None),
        ("Comp_Orig_ReduceO", torch.compile(calculate_token_entropy, mode="reduce-overhead"), None),
        ("Comp_Orig_MaxTune", torch.compile(calculate_token_entropy, mode="max-autotune"), None),
    ]

    results = []
    for name, fn, _ in configs:
        try:
            fn(logits, temp)
            ms = benchmark(fn, logits, temp)
            results.append((name, ms))
        except Exception as e:
            results.append((name, None, str(e)[:50]))

    baseline_orig = next(ms for name, ms in results if name == "Eager_Orig")

    # ------ 0. Print speedup result ------
    for row in results:
        if len(row) == 3:
            name, _, err = row
            print(f"{name:20s}: Failed -> {err}")
        else:
            name, ms = row
            baseline = baseline_orig
            speedup = baseline / ms
            print(f"{name:20s}: {ms:8.4f} ms  speedup={speedup:.3f}x")
   
if __name__ == "__main__":
    main()

---

Device: cuda | Dtype: torch.float16 | Batch: 1
Eager_Orig : 0.0792 ms speedup=1.000x
Comp_Orig_Default : 0.1407 ms speedup=0.563x
Comp_Orig_ReduceO : 0.0934 ms speedup=0.848x
Comp_Orig_MaxTune : 0.0843 ms speedup=0.939x

Device: cuda | Dtype: torch.float16 | Batch: 8
Eager_Orig : 0.0801 ms speedup=1.000x
Comp_Orig_Default : 0.1409 ms speedup=0.568x
Comp_Orig_ReduceO : 0.0961 ms speedup=0.833x
Comp_Orig_MaxTune : 0.1547 ms speedup=0.517x

Device: cuda | Dtype: torch.float16 | Batch: 64
Eager_Orig : 0.0650 ms speedup=1.000x
Comp_Orig_Default : 0.1381 ms speedup=0.470x
Comp_Orig_ReduceO : 0.0846 ms speedup=0.768x
Comp_Orig_MaxTune : 0.1195 ms speedup=0.544x

Device: cuda | Dtype: torch.float16 | Batch: 512
Eager_Orig : 1.2873 ms speedup=1.000x
Comp_Orig_Default : 0.1758 ms speedup=7.321x
Comp_Orig_ReduceO : 0.4532 ms speedup=2.840x
Comp_Orig_MaxTune : 0.4396 ms speedup=2.928x

---

Collecting environment information...
PyTorch version: 2.10.0.dev20251021+cu128
Is debug build: False
CUDA used to build PyTorch: 12.8
ROCM used to build PyTorch: N/A

OS: Ubuntu 22.04.4 LTS (x86_64)
GCC version: (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
Clang version: Could not collect
CMake version: version 3.22.1
Libc version: glibc-2.35

Python version: 3.10.19 (main, Oct 21 2025, 16:43:05) [GCC 11.2.0] (64-bit runtime)
Python platform: Linux-6.8.0-40-generic-x86_64-with-glibc2.35
Is CUDA available: True
CUDA runtime version: 11.8.89
CUDA_MODULE_LOADING set to:
GPU models and configuration:
GPU 0: NVIDIA RTX A6000
GPU 1: NVIDIA RTX A6000

Nvidia driver version: 570.211.01
cuDNN version: Could not collect
Is XPU available: False
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True
Caching allocator config: N/A

CPU:
Architecture:                         x86_64
CPU op-mode(s):                       32-bit, 64-bit
Address sizes:                        46 bits physical, 48 bits virtual
Byte Order:                           Little Endian
CPU(s):                               96
On-line CPU(s) list:                  0-95
Vendor ID:                            GenuineIntel
Model name:                           Intel(R) Xeon(R) Gold 6248R CPU @ 3.00GHz
CPU family:                           6
Model:                                85
Thread(s) per core:                   2
Core(s) per socket:                   24
Socket(s):                            2
Stepping:                             7
BogoMIPS:                             6000.00
Flags:                                fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts vnmi pku ospke avx512_vnni md_clear flush_l1d arch_capabilities
Virtualization:                       VT-x
L1d cache:                            1.5 MiB (48 instances)
L1i cache:                            1.5 MiB (48 instances)
L2 cache:                             48 MiB (48 instances)
L3 cache:                             71.5 MiB (2 instances)
NUMA node(s):                         2
NUMA node0 CPU(s):                    0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94
NUMA node1 CPU(s):                    1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95
Vulnerability Gather data sampling:   Mitigation; Microcode
Vulnerability Itlb multihit:          KVM: Mitigation: VMX disabled
Vulnerability L1tf:                   Not affected
Vulnerability Mds:                    Not affected
Vulnerability Meltdown:               Not affected
Vulnerability Mmio stale data:        Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed:               Mitigation; Enhanced IBRS
Vulnerability Spec rstack overflow:   Not affected
Vulnerability Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:             Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:             Mitigation; Enhanced / Automatic IBRS; IBPB conditional; RSB filling; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop
Vulnerability Srbds:                  Not affected
Vulnerability Tsx async abort:        Mitigation; TSX disabled

Versions of relevant libraries:
[pip3] numpy==2.2.6
[pip3] nvidia-cublas-cu11==11.11.3.6
[pip3] nvidia-cublas-cu12==12.8.4.1
[pip3] nvidia-cuda-cupti-cu11==11.8.87
[pip3] nvidia-cuda-cupti-cu12==12.8.90
[pip3] nvidia-cuda-nvrtc-cu11==11.8.89
[pip3] nvidia-cuda-nvrtc-cu12==12.8.93
[pip3] nvidia-cuda-runtime-cu11==11.8.89
[pip3] nvidia-cuda-runtime-cu12==12.8.90
[pip3] nvidia-cudnn-cu11==9.1.0.70
[pip3] nvidia-cudnn-cu12==9.10.2.21
[pip3] nvidia-cufft-cu11==10.9.0.58
[pip3] nvidia-cufft-cu12==11.3.3.83
[pip3] nvidia-curand-cu11==10.3.0.86
[pip3] nvidia-curand-cu12==10.3.9.90
[pip3] nvidia-cusolver-cu11==11.4.1.48
[pip3] nvidia-cusolver-cu12==11.7.3.90
[pip3] nvidia-cusparse-cu11==11.7.5.86
[pip3] nvidia-cusparse-cu12==12.5.8.93
[pip3] nvidia-cusparselt-cu12==0.7.1
[pip3] nvidia-nccl-cu11==2.21.5
[pip3] nvidia-nccl-cu12==2.27.5
[pip3] nvidia-nvjitlink-cu12==12.8.93
[pip3] nvidia-nvtx-cu11==11.8.86
[pip3] nvidia-nvtx-cu12==12.8.90
[pip3] pytorch-triton==3.5.0+git7416ffcb
[pip3] torch==2.10.0.dev20251021+cu128
[pip3] torchaudio==2.10.0.dev20251021+cu128
[pip3] torchvision==0.25.0.dev20251021+cu128
[pip3] triton==3.0.0
[conda] numpy                     2.2.6                    pypi_0    pypi
[conda] nvidia-cublas-cu11        11.11.3.6                pypi_0    pypi
[conda] nvidia-cublas-cu12        12.8.4.1                 pypi_0    pypi
[conda] nvidia-cuda-cupti-cu11    11.8.87                  pypi_0    pypi
[conda] nvidia-cuda-cupti-cu12    12.8.90                  pypi_0    pypi
[conda] nvidia-cuda-nvrtc-cu11    11.8.89                  pypi_0    pypi
[conda] nvidia-cuda-nvrtc-cu12    12.8.93                  pypi_0    pypi
[conda] nvidia-cuda-runtime-cu11  11.8.89                  pypi_0    pypi
[conda] nvidia-cuda-runtime-cu12  12.8.90                  pypi_0    pypi
[conda] nvidia-cudnn-cu11         9.1.0.70                 pypi_0    pypi
[conda] nvidia-cudnn-cu12         9.10.2.21                pypi_0    pypi
[conda] nvidia-cufft-cu11         10.9.0.58                pypi_0    pypi
[conda] nvidia-cufft-cu12         11.3.3.83                pypi_0    pypi
[conda] nvidia-curand-cu11        10.3.0.86                pypi_0    pypi
[conda] nvidia-curand-cu12        10.3.9.90                pypi_0    pypi
[conda] nvidia-cusolver-cu11      11.4.1.48                pypi_0    pypi
[conda] nvidia-cusolver-cu12      11.7.3.90                pypi_0    pypi
[conda] nvidia-cusparse-cu11      11.7.5.86                pypi_0    pypi
[conda] nvidia-cusparse-cu12      12.5.8.93                pypi_0    pypi
[conda] nvidia-cusparselt-cu12    0.7.1                    pypi_0    pypi
[conda] nvidia-nccl-cu11          2.21.5                   pypi_0    pypi
[conda] nvidia-nccl-cu12          2.27.5                   pypi_0    pypi
[conda] nvidia-nvjitlink-cu12     12.8.93                  pypi_0    pypi
[conda] nvidia-nvtx-cu11          11.8.86                  pypi_0    pypi
[conda] nvidia-nvtx-cu12          12.8.90                  pypi_0    pypi
[conda] pytorch-triton            3.5.0+git7416ffcb          pypi_0    pypi
[conda] torch                     2.10.0.dev20251021+cu128          pypi_0    pypi
[conda] torchaudio                2.10.0.dev20251021+cu128          pypi_0    pypi
[conda] torchvision               0.25.0.dev20251021+cu128          pypi_0    pypi
RAW_BUFFERClick to expand / collapse

🐛 Describe the bug

When using torch.compile on a Token Entropy calculation function, there is a significant performance degradation compared to eager execution, especially when the Batch Size is small (e.g., 1 to 64).

I guess torch.compile actually introduces overhead that makes it ~2x slower in low-latency scenarios. The performance only starts to show gains when the Batch Size is increased to 512.

Minimal reproduce code:

import argparse
import time
import torch
import torch.nn.functional as F
import torch.nn as nn

def calculate_token_entropy(
    logits: torch.Tensor, temperature: float = 1.0
) -> torch.Tensor:
    if temperature == 0.0:
        if logits.dim() == 1:
            return torch.tensor(0.0, device=logits.device)
        return torch.zeros(logits.shape[0], device=logits.device)

    scaled_logits = logits / temperature
    probs = torch.softmax(scaled_logits, dim=-1)
    log_probs = torch.log_softmax(scaled_logits, dim=-1)  
    entropy = -torch.sum(probs * log_probs, dim=-1)
    return entropy

def benchmark(fn, logits, temp, warmup=20, iters=100):
    for _ in range(warmup):
        fn(logits, temp)
    
    if torch.cuda.is_available():
        torch.cuda.synchronize()
    
    start_time = time.perf_counter()
    for _ in range(iters):
        fn(logits, temp)
    
    if torch.cuda.is_available():
        torch.cuda.synchronize()
    end_time = time.perf_counter()
    
    return ((end_time - start_time) / iters) * 1000

def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("--batch-size", type=int, default=1)
    parser.add_argument("--vocab-size", type=int, default=32768)
    parser.add_argument("--device", type=str, default="cuda" if torch.cuda.is_available() else "cpu")
    parser.add_argument("--dtype", type=str, default="float16")
    args = parser.parse_args()

    device = torch.device(args.device)
    dtype = torch.float16 if args.dtype == "float16" else torch.float32
    
    logits = torch.randn(args.batch_size, args.vocab_size, device=device, dtype=dtype)
    temp = 1.0

    print(f"Device: {device} | Dtype: {dtype} | Batch: {args.batch_size}")

    configs = [
        ("Eager_Orig", calculate_token_entropy, None),
        ("Comp_Orig_Default", torch.compile(calculate_token_entropy), None),
        ("Comp_Orig_ReduceO", torch.compile(calculate_token_entropy, mode="reduce-overhead"), None),
        ("Comp_Orig_MaxTune", torch.compile(calculate_token_entropy, mode="max-autotune"), None),
    ]

    results = []
    for name, fn, _ in configs:
        try:
            fn(logits, temp)
            ms = benchmark(fn, logits, temp)
            results.append((name, ms))
        except Exception as e:
            results.append((name, None, str(e)[:50]))

    baseline_orig = next(ms for name, ms in results if name == "Eager_Orig")

    # ------ 0. Print speedup result ------
    for row in results:
        if len(row) == 3:
            name, _, err = row
            print(f"{name:20s}: Failed -> {err}")
        else:
            name, ms = row
            baseline = baseline_orig
            speedup = baseline / ms
            print(f"{name:20s}: {ms:8.4f} ms  speedup={speedup:.3f}x")
   
if __name__ == "__main__":
    main()

Test are run under different batch sizes. For Batch Size 1-64, all torch.compile modes (Default, Reduce-Overhead, Max-Autotune) are significantly slower than Eager mode. The compiler works as expected at Batch Size 512

Output:

Device: cuda | Dtype: torch.float16 | Batch: 1
Eager_Orig : 0.0792 ms speedup=1.000x
Comp_Orig_Default : 0.1407 ms speedup=0.563x
Comp_Orig_ReduceO : 0.0934 ms speedup=0.848x
Comp_Orig_MaxTune : 0.0843 ms speedup=0.939x

Device: cuda | Dtype: torch.float16 | Batch: 8
Eager_Orig : 0.0801 ms speedup=1.000x
Comp_Orig_Default : 0.1409 ms speedup=0.568x
Comp_Orig_ReduceO : 0.0961 ms speedup=0.833x
Comp_Orig_MaxTune : 0.1547 ms speedup=0.517x

Device: cuda | Dtype: torch.float16 | Batch: 64
Eager_Orig : 0.0650 ms speedup=1.000x
Comp_Orig_Default : 0.1381 ms speedup=0.470x
Comp_Orig_ReduceO : 0.0846 ms speedup=0.768x
Comp_Orig_MaxTune : 0.1195 ms speedup=0.544x

Device: cuda | Dtype: torch.float16 | Batch: 512
Eager_Orig : 1.2873 ms speedup=1.000x
Comp_Orig_Default : 0.1758 ms speedup=7.321x
Comp_Orig_ReduceO : 0.4532 ms speedup=2.840x
Comp_Orig_MaxTune : 0.4396 ms speedup=2.928x

Versions

Collecting environment information...
PyTorch version: 2.10.0.dev20251021+cu128
Is debug build: False
CUDA used to build PyTorch: 12.8
ROCM used to build PyTorch: N/A

OS: Ubuntu 22.04.4 LTS (x86_64)
GCC version: (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
Clang version: Could not collect
CMake version: version 3.22.1
Libc version: glibc-2.35

Python version: 3.10.19 (main, Oct 21 2025, 16:43:05) [GCC 11.2.0] (64-bit runtime)
Python platform: Linux-6.8.0-40-generic-x86_64-with-glibc2.35
Is CUDA available: True
CUDA runtime version: 11.8.89
CUDA_MODULE_LOADING set to:
GPU models and configuration:
GPU 0: NVIDIA RTX A6000
GPU 1: NVIDIA RTX A6000

Nvidia driver version: 570.211.01
cuDNN version: Could not collect
Is XPU available: False
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True
Caching allocator config: N/A

CPU:
Architecture:                         x86_64
CPU op-mode(s):                       32-bit, 64-bit
Address sizes:                        46 bits physical, 48 bits virtual
Byte Order:                           Little Endian
CPU(s):                               96
On-line CPU(s) list:                  0-95
Vendor ID:                            GenuineIntel
Model name:                           Intel(R) Xeon(R) Gold 6248R CPU @ 3.00GHz
CPU family:                           6
Model:                                85
Thread(s) per core:                   2
Core(s) per socket:                   24
Socket(s):                            2
Stepping:                             7
BogoMIPS:                             6000.00
Flags:                                fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced tpr_shadow flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts vnmi pku ospke avx512_vnni md_clear flush_l1d arch_capabilities
Virtualization:                       VT-x
L1d cache:                            1.5 MiB (48 instances)
L1i cache:                            1.5 MiB (48 instances)
L2 cache:                             48 MiB (48 instances)
L3 cache:                             71.5 MiB (2 instances)
NUMA node(s):                         2
NUMA node0 CPU(s):                    0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94
NUMA node1 CPU(s):                    1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95
Vulnerability Gather data sampling:   Mitigation; Microcode
Vulnerability Itlb multihit:          KVM: Mitigation: VMX disabled
Vulnerability L1tf:                   Not affected
Vulnerability Mds:                    Not affected
Vulnerability Meltdown:               Not affected
Vulnerability Mmio stale data:        Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed:               Mitigation; Enhanced IBRS
Vulnerability Spec rstack overflow:   Not affected
Vulnerability Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:             Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:             Mitigation; Enhanced / Automatic IBRS; IBPB conditional; RSB filling; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop
Vulnerability Srbds:                  Not affected
Vulnerability Tsx async abort:        Mitigation; TSX disabled

Versions of relevant libraries:
[pip3] numpy==2.2.6
[pip3] nvidia-cublas-cu11==11.11.3.6
[pip3] nvidia-cublas-cu12==12.8.4.1
[pip3] nvidia-cuda-cupti-cu11==11.8.87
[pip3] nvidia-cuda-cupti-cu12==12.8.90
[pip3] nvidia-cuda-nvrtc-cu11==11.8.89
[pip3] nvidia-cuda-nvrtc-cu12==12.8.93
[pip3] nvidia-cuda-runtime-cu11==11.8.89
[pip3] nvidia-cuda-runtime-cu12==12.8.90
[pip3] nvidia-cudnn-cu11==9.1.0.70
[pip3] nvidia-cudnn-cu12==9.10.2.21
[pip3] nvidia-cufft-cu11==10.9.0.58
[pip3] nvidia-cufft-cu12==11.3.3.83
[pip3] nvidia-curand-cu11==10.3.0.86
[pip3] nvidia-curand-cu12==10.3.9.90
[pip3] nvidia-cusolver-cu11==11.4.1.48
[pip3] nvidia-cusolver-cu12==11.7.3.90
[pip3] nvidia-cusparse-cu11==11.7.5.86
[pip3] nvidia-cusparse-cu12==12.5.8.93
[pip3] nvidia-cusparselt-cu12==0.7.1
[pip3] nvidia-nccl-cu11==2.21.5
[pip3] nvidia-nccl-cu12==2.27.5
[pip3] nvidia-nvjitlink-cu12==12.8.93
[pip3] nvidia-nvtx-cu11==11.8.86
[pip3] nvidia-nvtx-cu12==12.8.90
[pip3] pytorch-triton==3.5.0+git7416ffcb
[pip3] torch==2.10.0.dev20251021+cu128
[pip3] torchaudio==2.10.0.dev20251021+cu128
[pip3] torchvision==0.25.0.dev20251021+cu128
[pip3] triton==3.0.0
[conda] numpy                     2.2.6                    pypi_0    pypi
[conda] nvidia-cublas-cu11        11.11.3.6                pypi_0    pypi
[conda] nvidia-cublas-cu12        12.8.4.1                 pypi_0    pypi
[conda] nvidia-cuda-cupti-cu11    11.8.87                  pypi_0    pypi
[conda] nvidia-cuda-cupti-cu12    12.8.90                  pypi_0    pypi
[conda] nvidia-cuda-nvrtc-cu11    11.8.89                  pypi_0    pypi
[conda] nvidia-cuda-nvrtc-cu12    12.8.93                  pypi_0    pypi
[conda] nvidia-cuda-runtime-cu11  11.8.89                  pypi_0    pypi
[conda] nvidia-cuda-runtime-cu12  12.8.90                  pypi_0    pypi
[conda] nvidia-cudnn-cu11         9.1.0.70                 pypi_0    pypi
[conda] nvidia-cudnn-cu12         9.10.2.21                pypi_0    pypi
[conda] nvidia-cufft-cu11         10.9.0.58                pypi_0    pypi
[conda] nvidia-cufft-cu12         11.3.3.83                pypi_0    pypi
[conda] nvidia-curand-cu11        10.3.0.86                pypi_0    pypi
[conda] nvidia-curand-cu12        10.3.9.90                pypi_0    pypi
[conda] nvidia-cusolver-cu11      11.4.1.48                pypi_0    pypi
[conda] nvidia-cusolver-cu12      11.7.3.90                pypi_0    pypi
[conda] nvidia-cusparse-cu11      11.7.5.86                pypi_0    pypi
[conda] nvidia-cusparse-cu12      12.5.8.93                pypi_0    pypi
[conda] nvidia-cusparselt-cu12    0.7.1                    pypi_0    pypi
[conda] nvidia-nccl-cu11          2.21.5                   pypi_0    pypi
[conda] nvidia-nccl-cu12          2.27.5                   pypi_0    pypi
[conda] nvidia-nvjitlink-cu12     12.8.93                  pypi_0    pypi
[conda] nvidia-nvtx-cu11          11.8.86                  pypi_0    pypi
[conda] nvidia-nvtx-cu12          12.8.90                  pypi_0    pypi
[conda] pytorch-triton            3.5.0+git7416ffcb          pypi_0    pypi
[conda] torch                     2.10.0.dev20251021+cu128          pypi_0    pypi
[conda] torchaudio                2.10.0.dev20251021+cu128          pypi_0    pypi
[conda] torchvision               0.25.0.dev20251021+cu128          pypi_0    pypi

extent analysis

TL;DR

The performance degradation with torch.compile for small batch sizes can be mitigated by using the "reduce-overhead" mode, which shows better performance compared to the default compilation mode for batch sizes 1-64.

Guidance

  • The provided benchmark results indicate that torch.compile introduces significant overhead for small batch sizes, making it slower than eager execution.
  • Using the "reduce-overhead" mode with torch.compile can help alleviate this issue, as seen in the benchmark results where Comp_Orig_ReduceO outperforms Comp_Orig_Default for batch sizes 1-64.
  • For larger batch sizes (e.g., 512), the default compilation mode and "max-autotune" mode show better performance, indicating that the overhead of compilation is outweighed by the benefits of optimized execution.
  • To further investigate, try experimenting with different compilation modes and batch sizes to find the optimal configuration for your specific use case.

Example

No specific code example is provided, as the issue is more related to the configuration and usage of torch.compile rather than a code snippet.

Notes

The performance difference between torch.compile and eager execution may vary depending on the specific hardware, PyTorch version, and use case. The provided benchmark results are specific to the described environment and may not generalize to other setups.

Recommendation

Apply the "reduce-overhead" mode with torch.compile for small batch sizes (e.g., 1-64) to mitigate the performance degradation. For larger batch sizes, consider using the default compilation mode or "max-autotune" mode for potentially better performance.

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